Liquid storage tanks, such as those used on fire engines, have high strength requirements due to the weight of the liquid stored in the tanks. Liquid storage tanks for fire engines, for example, can hold a 1000 gallons or more of water and must obviously do so with high reliability.
Such liquid storage tanks have been developed with side, bottom and top pieces welded together to form the tank. These pieces are hand welded together by a traditional weld. The sides and the bottom are welded together by a hot tip hand welder guided along the side-bottom seam while the operator hand pushes a round welding rod into the hand welder. The welder melts the welding rods and applies them to the interior junctions between the sides and the bottom. The welds hold the sides, bottom and top pieces together under the force of water weight. Improvements in strength are desirable in order to increase tank capacities and reduce material costs.
A traditional technique for forming such liquid storage tanks is shown in U.S. Pat. No. 5,820,718, issued on Oct. 13, 1998 to T. S. Dean. As shown in FIG. 1 of this patent, the floor of the tank is placed on a support surface and the sides and ends are welded internally to the floor. A lid is then placed onto the opposite ends of the sides and ends and is welded to the sides and the ends by placing the lid a small distance below an upper edge of the sides and ends. In this manner, a single external weld is applied between the lid and the sides and ends. In this traditional technique of forming liquid storage tanks, it is only possible to apply a single external weld between the lid and the sides and the ends. As such, the strength of an interior weld is not made available. During emergency braking or rapid acceleration of the fire truck (or other apparatus), extra force and water pressure is applied to the tank's end walls and lid. This can cause the seams to split and possibly rupture. The tank lid is only welded on the outside edge and then welded to junction plates or pegs. Furthermore, because of the structure of such liquid storage tanks, it is impossible to weld the lid internally to such sides and ends. Additionally, all internal support gussets and baffles cannot be attached directly onto the lid. Since the lid is recessed, the lid will allow water to accumulate and possibly damage any equipment stored on the top of the tank.
It is an object of the present invention to provide a liquid storage tank in which all seams between the lid, the floor, the sides and the ends are welded internally.
It is another object of the present invention to provide a liquid storage tank in which the lid is not mounted flush to or above the sides so that water cannot accumulate thereon.
It is another object of the present invention to provide suitable gussets which connect the lid, the side walls and the floor together.
It is a further object of the present invention to provide a liquid storage tank in which baffles control water surge in the event of emergency braking or rapid acceleration.
It is still another object of the present invention to provide a liquid storage tank which has an access panel that can be modified for easy removal so as to facilitate repair of the baffles.
It is still another object of the present invention to provide a liquid storage tank which is stronger and more durable than existing designs.
It is still another object of the present invention to provide a liquid storage tank which is easy to manufacture and relatively inexpensive.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.